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1) 2,75 - 5/6 × 2/5 = 2,75 - (5/6) × (2/5) = 2,75 - 1/3 = 2,75 - 0,33 = 2,42
2) 1,25 - (5/6 - 0,75) - 3/5 = 1,25 - (5/6 - 0,75) - 3/5 = 1,25 - (5/6 - 3/4) - 3/5 = 1,25 - (5/6 - 9/12) - 3/5 = 1,25 - (10/12 - 9/12) - 3/5 = 1,25 - 1/12 - 3/5 = 1,25 - 0,08 - 0,6 = 1,25 - 0,68 = 0,57
3) 4/9 × 0,75 + 8/5 + 3,125 = (4/9) × 0,75 + 8/5 + 3,125 = 0,44 + 8/5 + 3,125 = 0,44 + 1,6 + 3,125 = 0,44 + 4,725 = 5,165
4) 1,125 - 4/7 - 0,12 = 1,125 - (4/7) - 0,12 = 1,125 - 0,57 - 0,12 = 0,435 - 0,12 = 0,315
5) (1/3 + 0,4) × 3,5 + (1/6 + 0,75) × 6/5
a) 4/7 x X = 1/5 + 2/3
=> 4/7 x X = 3/15 + 10/15
=> 4/7 x X = 13/15
=> X = 13/15 : 4/7
=> X = 13/15 x 4/7 = 52/105
a ) 4 / 7 x X = 1 / 5 + 2 / 3
= > 4 / 7 x X = 3 / 1 5 + 1 0 / 1 5
= > 4 / 7 x X = 1 3 / 1 5
= > X = 1 3 / 1 5 : 4 / 7
= > X = 1 3 / 1 5 x 4 / 7
= 5 2 / 1 0 5
\(x+\frac{2}{5}=\frac{9}{2}.\frac{1}{6}\)
\(x+\frac{2}{5}=\frac{3}{4}\)
\(x=\frac{3}{4}-\frac{2}{5}\)
\(x=\frac{7}{20}\)
`@` `\text {Ans}`
`\downarrow`
`a)`
\(\dfrac{3}{2}\times\dfrac{4}{5}-x=\dfrac{2}{3}\)
\(\dfrac{6}{5}-x=\dfrac{2}{3}\)
\(x=\dfrac{6}{5}-\dfrac{2}{3}\)
\(x=\dfrac{18}{15}-\dfrac{10}{15}\)
\(x=\dfrac{8}{15}\)
Vậy, `x =`\(\dfrac{8}{15}\)
`b)`
\(x\times3\dfrac{1}{3}=3\dfrac{1}{3}\div4\dfrac{1}{4}\)
\(x\times\dfrac{10}{3}=\dfrac{40}{51}\)
\(x=\dfrac{40}{51}\div\dfrac{10}{3}\)
\(x=\dfrac{4}{17}\)
Vậy, \(x=\dfrac{4}{17}\)
`c)`
\(5\dfrac{2}{3}\div x=3\dfrac{2}{3}-2\dfrac{1}{2}\)
\(\dfrac{17}{3}\div x=\dfrac{7}{6}\)
\(x=\dfrac{17}{3}\div\dfrac{7}{6}\)
\(x=\dfrac{34}{7}\)
Vậy, `x = `\(\dfrac{34}{7}\)
a) \(\dfrac{3}{2}x\dfrac{4}{5}-x=\dfrac{2}{3}\Rightarrow\dfrac{6}{5}-x=\dfrac{2}{3}\Rightarrow x=\dfrac{6}{5}-\dfrac{2}{3}=\dfrac{18}{15}-\dfrac{10}{15}=\dfrac{8}{15}\)
b) \(x.3\dfrac{1}{3}=3\dfrac{1}{3}:4\dfrac{1}{4}\Rightarrow\dfrac{10}{3}.x=\dfrac{10}{3}:\dfrac{17}{4}\Rightarrow\dfrac{10}{3}.x=\dfrac{10}{3}.\dfrac{4}{17}\Rightarrow x=\dfrac{10}{3}.\dfrac{4}{17}:\dfrac{10}{3}=\dfrac{10}{3}.\dfrac{4}{17}.\dfrac{3}{10}=\dfrac{4}{17}\)
c) \(5\dfrac{2}{3}:x=3\dfrac{2}{3}-2\dfrac{1}{2}\Rightarrow\dfrac{17}{3}:x=\dfrac{11}{3}-\dfrac{5}{2}\Rightarrow\dfrac{17}{3}:x=\dfrac{22}{6}-\dfrac{15}{6}\Rightarrow\dfrac{17}{3}:x=\dfrac{7}{6}\Rightarrow x=\dfrac{17}{3}:\dfrac{7}{6}=\dfrac{17}{3}.\dfrac{7}{6}=\dfrac{119}{18}\)
\(\frac{2}{5}\cdot\frac{1}{2}-\frac{2}{5}\cdot\frac{1}{3}-\frac{2}{5}\cdot\frac{1}{6}\)
\(=\frac{2}{5}\cdot\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)
\(=\frac{2}{5}\cdot\frac{0}{6}=\frac{2}{5}\cdot0=0\)
tìm x
a) \(0,5+\left(x-\frac{15}{2}\right):\frac{1}{2}=\frac{9}{2}\)
\(\Rightarrow x=\frac{19}{2}=8,5\)
b) \(2012\cdot x-2010\cdot x=2014\)
\(\Leftrightarrow\left(2012-1010\right)\cdot x=2014\)
\(\Leftrightarrow2x=2014\)
\(\Rightarrow x=\frac{2014}{2}=1007\)
hok tốt .
Tính nhanh:
2/5 x 1/2 - 2/5 x 1/3 - 2/5 x 1/6
= 2/5 x ( 1/2 - 1/3 - 1/6 )
= 2/5 x ( 3/6 - 2/6 - 1/6 )
= 2/5 x 0/6
=0
a) x + 1/15 = 1/3 - 1/4 = 4/12 - 3/12 = 1/12.
=> x = 1/12 - 1/15 = 5/60 - 4/60 = 1/60.
b) x - 5/12 = 1/3 + 1/4 = 4/12 + 3/12 = 7/12.
=> x = 7/12 + 5/12 = 1
c) x x 2/7 = 3/4 x 4/15 = 1/5
=> x = 1/5 : 2/7 = 1/5 x 7/2 = 7/10
d) x : 3/8 = 4/3 : 3/6 = 4/3 x 2 = 8/3
=> x = 8/3 x 3/8 = 1
(x/2-1/3).5/6-1/2=1/3
=>(x/2-1/3).5/6=1/3+1/2=5/6
=>x/2-1/3=5/6:5/6=1
=>x/2=1+1/3=4/3
=>x=4/3.2=8/3
vậy x=8/3
( x/2 - 1/3 ) . 5/6 - 1/2 = 1/3
( x/2 - 1/3 ) . 5/6 = 1/3 + 1/2
( x/2 - 1/3 ) . 5/6 = 5/6
( x/2 - 1/3 ) = 5/6 : 5/6
( x/2 - 1/3 ) = 1
x/2 = 1 + 1/3
x/2 = 4/3
x = 4/3 : 2
x = 2/3